The sum of the Christian life by John Calvin

The sum of the Christian life is denial of ourselves. The ends of this self-denial are four.

1. That we may devote ourselves to God as a living sacrifice.
   
2. That we may not seek our own things, but those which belong to God and to our neighbour.
   
3. That we may patiently bear the cross, the fruits of which are—acknowledgment of our weakness, the trial of our patience, correction of faults, more earnest prayer, more cheerful meditation on eternal life.
   
4. That we may know in what manner we ought to use the present life and its aids, for necessity and delight. Necessity demands that we possess all things as though we possessed them not; that we bear poverty with mildness, and abundance with moderation; that we know how to endure patiently fulness, and hunger, and want; that we pay regard to our neighbour, because we must give account of our stewardship; and that all things correspond to our calling. The delight of praising the kindness of God ought to be with us a stronger argument.

- Book III, Institutes of the Christian Religion, John Calvin (1509-1564)

Source: http://www.ccel.org/ccel/calvin/institutes.v.iii.html